The present invention relates to cell culture dishes. In particular, the invention relates to splash-guards that are removable from the rim of cell culture dishes. Splash-guards are designed to prevent liquid media from spilling out of relatively shallow culture dishes during the preparation and handling processes.
The use of culture plates, traditionally known as Petri dishes or culture dishes, to grow or culture bacteria, eukaryotic cells, viruses, or other microorganisms has been long practiced. A typical culture dish or plate is made of a clear plastic structure, having a cylindrical, rectangular or square base with an open top and a complementary or mating lid, which is configured to rest on the base and close off the opening.
In normal use, a number of culture plates are assembled together at one time in a batch operation. Each culture plate is loaded with a desired liquid growth medium, similar in viscosity to water. The plates are placed on a larger tray, and the tray is moved, usually by hand, from location to location or into and out of an incubator. During this handling, the tray of culture plates may stick in the incubator rack and require force to dislodge it, or the tray may bump into the side or rear walls of the incubator, both of which exerts a jarring force on the culture plates. This jarring force, or simple movement during handling, often causes the liquid media within each culture plate to move, resulting in the liquid media sloshing about in the plate. Since culture plates typically are relatively shallow basins or containers with a short, surrounding sidewall of a height of about 10 mm to about 25 mm, and a large, open surface area, it is very difficult to prevent the liquid media from splashing onto the lid or inside-base sidewalls and/or over the top edge of the base sidewall during movement. When liquid travels to the outer, non-sterile areas of a culture plate, a path is created for bacteria growth to travel to the other inside areas of the culture plate and to contaminate the contents of the plate. Alternatively, media from inside the plate can splash out of the plate, down the outside sidewall and into the incubator environment. Obviously, such contamination is an unacceptable for use. Media leakage provides nutrients for bacteria of fungi to grow outside the culture plate and further contaminate the otherwise clean environment inside an incubator.
The same contamination problems discussed above occur when a user handles an individual culture plate. Mere movement of the individual culture plate results in the splashing of liquid media. Moreover, if the culture plate is growing or includes a pathogenic or radioactive material, or other dangerous specimens, it is highly undesirable for the material to splash out of the culture plate onto the user or into the outside environment.
Raising the edges of the culture plate to make the plate deeper would minimize the problem of liquids splashing out of the plate. This approach, however, would not be conducive to mass processing a number of plates together, since the trays and storage density in the incubator are made for culture plates of standardized width, length, and height. Some current designs of standard height incorporate a beveled baffle or inner rim at the top edge or along the inside of the sidewall of a culture plate, such as described in U.S. Pat. No. 5,593,891 issued to Albert J. Banes. Having its advantages, this second approach, however, can create other problems with contamination from capillary wicking of the liquid media and cells into inaccessible recesses of the plate. A molded baffle or frame that is attached with a seal to the base plate would be subject to viscous media seepage into the seal. Any cells in the media trapped between the baffle and plate would die and contaminate potentially the entire culture. Additionally, mechanically affixing or welding a non-removable frame of plastic to the inner rim of a culture plate will likely restrict access to cells for microscopic viewing or during harvesting. Moreover, these types of design likely have associated manufacturing difficulties due to their rather complex shapes.
Hence, an objective of the present invention is to provide an improved splash-guards for conventional culture dishes, in which the flow of liquid over the top of the base side wall is eliminated or greatly reduced for all but the most violent movement of the dish. Another objective of the present invention to provide a culture plate or modification of existing culture plates in an arrangement that is reliable, easy to use, and inexpensive to manufacture. The invention can provide culture dishes that are pre-fitted with the inventive splash-guard. Further, a removable splash-guard design is more advantageous, since it would permit users to have better access to the entire surface area of a culture plate.
The present invention comprises a culture plate having an open-ended basin or container with a bottom wall, at least one sidewall extending upwardly from the bottom wall, and a splash guard that is removably attached to a top edge or rim of the sidewall. The splash-guard defines a frame-like structure with an open, central aperture and inwardly extending flanges that cover the top edges of the side wall and a peripheral portion of the bottom wall. The splash-guard is made of semi-rigid materials, such as plastics. When attached to the edge, the splash-guard remains in a horizontal plane relative to the open-end or mouth of the plate and does not dip within the volume defined by the side wall(s) of the culture plate. The splash-guard can be easily pealed off of the top of the open-end of the plate basin, starting with a pull-tab located near one comer. The splash-guard is also workable with common lid configurations, since it can easily fit or fold under the lid when the culture plate is covered.